Brian mac Cennétig, King of Munster

Brian Boru
18th-century imagined depiction of Brian Boru
High King of Ireland
Reign	1002 – 1014
Predecessor	Máel Sechnaill mac Domnaill
Successor	Máel Sechnaill mac Domnaill (restored)
King of Munster
Reign	978–1014
Predecessor	Máel Muad mac Brain
Successor	Dúngal mac Máelfothartaig Hua Donnchada
Born	ca. 941 Kincora, Killaloe, County Clare, Munster
Died	23 April 1014 Clontarf, Dublin, Leinster
Consort	Mór Echrad Gormflaith Dub Choblaig
Issue	Murchad Conchobar Flann Tadc Donnchad Domhnall Kerthialfad (adopted) Sadb Bé Binn Sláine
Father	Cennétig mac Lorcáin
Mother	Bé Binn inion Urchadh

Brian Boru (Old Irish: Brian Bóruma mac Cennétig; Middle Irish: Brian Bóruma; modern Irish: Brian Bóramha; c. 941 – 23 April 1014) was an Irish king who ended the domination of the High Kingship of Ireland by the Uí Néill. Building on the achievements of his father, Cennétig mac Lorcain, and especially his elder brother, Mathgamain, Brian first made himself King of Munster, then subjugated Leinster, eventually becoming King of Ireland. He was the founder of the O'Brien dynasty.

With a population of under 500,000 people, Ireland had over 150 kings, with greater or lesser domains. The Uí Néill king Máel Sechnaill mac Domnaill, abandoned by his northern kinsmen of the Cenél nEógain and Cenél Conaill, acknowledged Brian as High King at Athlone in 1002. In the decade that followed, Brian campaigned against the northern Uí Néill, who refused to accept his claims, against Leinster, where resistance was frequent, and against the Norse-Gaelic Kingdom of Dublin.

Brian's hard-won authority was seriously challenged in 1013 when his ally Máel Sechnaill was attacked by the Cenél nEógain king Flaithbertach Ua Néill, with the Ulstermen as his allies. This was followed by further attacks on Máel Sechnaill by the Dubliners under their king Sihtric Silkbeard and the Leinstermen led by Máel Mórda mac Murchada. Brian campaigned against these enemies in 1013. In 1014, Brian's armies confronted the armies of Leinster and Dublin, with Norsemen fighting on both sides, at Clontarf near Dublin on Good Friday. The resulting Battle of Clontarf was a bloody affair, with Brian, his son Murchad, and Máel Mórda among those killed. The list of the noble dead in the Annals of Ulster includes Irish kings, Norse Gaels, Scotsmen, and Scandinavians.